Hospital bed obstacle detection device and method

ABSTRACT

A hospital bed obstacle detection device and related method for detecting an obstacle between first and second components of a hospital bed is provided.

This application is a continuation of U.S. application Ser. No.10/510,996, which is to issue as U.S. Pat. No. 7,472,437 on Jan. 6, 2009and which is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/US03/12166, which has an Internationalfiling date of Apr. 21, 2003, designating the United States of America,and claims the benefit of U.S. Provisional Patent Application No.60/373,819, which was filed Apr. 19, 2002, and U.S. Provisional PatentApplication No. 60/408,698, which was filed Sep. 6, 2002.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates generally to a patient support and, moreparticularly, to a device and related method for detecting obstacleswithin a path of travel intermediate first and second components of ahospital bed. Further, the present invention relates to a device andrelated method for inhibiting the relative movement between first andsecond components of the hospital bed upon detection of an obstaclewithin the path of travel.

It is well known to provide a vertically movable patient support. Moreparticularly, it is known to provide a hospital bed including a baseframe and an elevating frame supporting a patient support surface. Alifting mechanism is configured to raise and lower the elevating framerelative to the base frame. Entry and exit from the bed is facilitatedby placing the elevating frame in a lowered position. A raised positionof the elevating frame, in turn, provides a convenient surface for theexamination and treatment of the patient.

Additionally, conventional lifting mechanisms provide for the tilting ofthe elevating frame from a horizontal position into Trendelenburg andreverse Trendelenburg positions. A hospital bed incorporating such alifting mechanism is illustrated in U.S. Pat. No. 3,958,283 to Adams etal., the disclosure of which is expressly incorporated by referenceherein.

According to an illustrative embodiment of the invention, a hospital bedobstacle detection device is provided for use with a hospital bedincluding a base frame and an elevating frame coupled to a patientsupport surface. The obstacle detection device controls movement of theelevating frame relative to the base frame upon detecting an objectwithin a path of travel of the elevating frame. The obstacle detectiondevice comprises an emitter coupled to one of the base frame and theelevating frame. The emitter is configured to generate a wirelesscurtain extending below the elevating frame. The obstacle detectiondevice further comprises a receiver coupled to one of the base frame andthe elevating frame of the bed. The receiver is configured to detect thewireless curtain generated by the emitter. The obstacle detection devicefurther comprises a control unit in communication with the receiver andconfigured to control movement of the elevating frame based on an outputsignal from the receiver.

Illustratively according to the invention, the emitter comprises aninfrared light source and a lens positioned proximate the infrared lightsource configured to convert light emitted therefrom to form an opticalcurtain. Illustratively, the lens comprises a fresnel lens.

Further illustratively according to the invention, the wireless curtainincludes a modulated signal and the receiver compares the modulatedsignal to a predefined verification signal in order to preventinterference from external light sources.

Illustratively according to the invention, the receiver is configured tomove with the elevating frame within a predefined vertical range. Thepredefined vertical range is illustratively from the base frame to theelevating frame when the elevating frame is in a fully raised position.

Further illustratively according to the invention, an indicator isprovided in communication with the control unit. The indicator isconfigured to indicate failure of the receiver to detect the wirelesscurtain.

According to a further illustrative embodiment of the invention, apatient support apparatus comprises a base frame, an elevating frameconfigured to move along a path of travel above the base frame, apatient support surface supported by the elevating frame, and a detectorsupported by one of the elevating frame and the base frame, the detectorbeing configured to detect an obstacle within the path of travel of theelevating frame and provide a control signal in response thereto. Acontrol unit is provided in communication with the detector and isconfigured to prevent movement of the elevating frame in response to thecontrol signal.

Illustratively according to the invention, an emitter is supported byone of the base frame and the elevating frame, wherein the emitter isconfigured to generate a wireless signal.

Further illustratively according to the invention, the emitter issupported by the base frame and the detector is supported for movementwith the elevating frame.

Illustratively according to the invention, the detector comprises acamera configured to capture images of the elevating frame along thepath of travel. The control unit is configured to compare the imagescaptured by the camera to predefined images to determine the presence ofan obstacle within the path of travel.

According to another illustrative embodiment of the invention, a patientsupport apparatus comprises a base frame, an elevating frame disposed inspaced relation to the base frame, a patient support surface supportedby the elevating frame, and an emitter coupled to one of the base frameand the elevating frame and configured to generate a wireless signal. Areceiver is coupled to one of the base frame and the elevating frame andis configured to detect the wireless signal.

Illustratively according to the invention, the patient support apparatusincludes a lifting device configured to move the elevating framerelative to the base frame.

Further illustratively according to the invention, the patient supportapparatus includes a control unit in communication with the liftingdevice and the receiver. The control unit is configured to preventoperation of the lifting device if the receiver fails to detect thewireless signal.

Illustratively according to the invention, the emitter generates anoptical curtain positioned intermediate the base frame and the elevatingframe. The emitter illustratively comprises an infrared light source anda lens is positioned proximate the infrared light source configured toconvert light emitted therefrom to the optical curtain. Illustratively,the lens comprises a fresnel lens.

Further illustratively according to the invention, the wireless signalincludes a modulated signal and the control unit compares the modulatedsignal to a predefined verification signal in order to preventinterference from external light sources.

Further illustratively according to the invention, the receiver isconfigured to move with the elevating frame within a predefined verticalrange. The predefined vertical range is illustratively from the baseframe to the elevating frame when the elevating frame is in a fullyraised position.

Illustratively according to the invention, an indicator is provided incommunication with the control unit. The indicator is configured toindicate failure of the receiver to detect a wireless signal.

Further illustratively according to the invention, the wireless signalincludes a pulsed portion having a predefined frequency, and saidreceiver is configured to detect said predefined frequency. The pulsedportion illustratively has a frequency of approximately 57 MHz and has aduration of approximately 600 microseconds followed by a delay ofapproximately 2 milliseconds.

Further illustratively according to the invention, the emitter isconfigured to generate a plurality of wireless signals in a plurality ofsignal paths, and a plurality of receivers are configured to detect thewireless signals along different ones of the signal paths. The controlunit is configured to prevent movement of the elevating frame when anyof the plurality of receivers fail to detect a wireless signal.

Illustratively according to the invention, at least one of the receiversis supported for movement with the elevating frame and the emitter issupported by the base frame.

According to another illustrative embodiment of the invention, ahospital bed obstacle detection device is provided for use with ahospital bed including a base frame and an elevating frame coupled to apatient support surface. The obstacle detection device is configured toprevent vertical movement of the elevating frame relative to the baseframe upon detecting an object within a path of travel of the elevatingframe. The obstacle detection device comprises at least one emitterconfigured to generate a first optical curtain extending proximate afirst longitudinal side edge of the bed intermediate the base frame andthe elevating frame, and a second optical curtain extending proximate asecond longitudinal side edge of the bed intermediate the base frame andthe elevating frame. The obstacle detection device further comprises atleast one first side receiver associated with the at least one emitterand configured to detect the first optical curtain, and at least onesecond side receiver associated with the at least one emitter andconfigured to detect the second optical curtain. A control unit isprovided in communication with the at least one first side receiver andthe at least one second side receiver, the control unit configured toprevent movement of the elevating frame if either of the at least onefirst side receiver and the at least one second side receiver does notdetect the first optical curtain and the second optical curtain,respectively.

Illustratively according to the invention, the emitter comprises aninfrared light source and a lens positioned proximate the infrared lightsource configured to convert light emitted therefrom to the opticalcurtain. Illustratively, the lens comprises a fresnel lens.

Illustratively according to the invention, each optical curtain includesa modulated signal and each receiver compares the modulated signal to apredefined verification signal to prevent interference from externallight sources.

Further illustratively according to the invention, each receiver isconfigured to move with the elevating frame within a predefined verticalrange. The predefined vertical range is illustratively from the baseframe to the elevating frame when the elevating frame is in a fullyraised position.

Illustratively according to the invention, an indicator is provided incommunication with the control unit. The indicator is configured toindicate failure of either of the first side and the second sidereceivers to detect the first and second optical curtains, respectively.

According to a further illustrative embodiment of the present invention,a hospital bed obstacle detection device is provided for use with ahospital bed including a base frame and an elevating frame coupled to apatient support surface. The obstacle detection device controls movementof the elevating frame relative to the base frame upon detecting anobject within a path of travel of the elevating frame. The obstacledetection device comprises means for generating a wireless curtainwithin a path of travel of the elevating frame, means for detecting thewireless curtain and generating a signal in response thereto, and meansfor receiving the signal and controlling movement of the elevating framein response thereto.

Illustratively according to the invention, the means for generating awireless curtain comprises an infrared light source. A lens isillustratively positioned proximate the infrared light source and isconfigured to convert light emitted therefrom to the wireless curtain.Illustratively the lens comprises a fresnel lens.

Further illustratively according to the invention, the wireless curtainincludes a modulated signal and the detecting means compares themodulated signal to a predefined signal to prevent interference fromexternal light sources.

Further illustratively according to the invention, the detecting meansis configured to move with the elevating frame within a predefinedvertical range. The predefined vertical range is illustratively from thebase frame to the elevating frame when the elevating frame is in a fullyraised position.

Illustratively according to the invention, an indicating means isprovided in communication with the control means. The indicating meansis configured to indicate failure of the detecting means to detect thewireless curtain.

According to another illustrative embodiment of the invention, a methodis provided of preventing vertical movement of a patient support surfaceupon detection of an obstacle within a path of travel, the methodcomprising the steps of providing a patient support including a movablecomponent, generating a detectable wireless signal within a path oftravel of the movable component, providing a receiver for detecting thewireless signal, moving the patient support surface, generating a stopsignal if the receiver fails to detect the wireless signal, andpreventing vertical movement of the patient support surface in responseto the stop signal.

Illustratively according to the invention, the step of generating adetectable wireless signal comprises the steps of providing a lightsource and emitting infrared light from the light source. The methodillustratively further comprises the step of placing a lens proximatethe light source for converting light emitted therefrom to an opticalcurtain.

Further illustratively according to the invention, the wireless signalincludes a modulated signal and the receiver compares the modulatedsignal to a predefined verification signal to prevent interference fromexternal light sources.

Illustratively according to the invention, the receiver is configured tomove with the elevating frame within a predefined vertical range.

Further illustratively according to the invention, the method comprisesthe step of activating an indicator in response to the stop signal.

According to a further illustrative embodiment of the invention, ahospital bed includes a first component, a second component movablerelative to the first component, an optical curtain generator coupled tothe first component, and an optical curtain detector coupled to thesecond component. The hospital bed further includes a control unit incommunication with the detector and being configured to prevent relativemovement of the first and second portions upon failure of the detectorto detect the optical curtain.

Illustratively according to the invention, the first component is one ofan elevating frame and an articulating deck supported by the elevatingframe, and the second component is the other of the elevating frame andthe articulating deck.

Illustratively according to the invention, the first component is one ofa base frame and an elevating frame supported by the base frame, and thesecond component is the other of the base frame and the elevating frame.

Illustratively according to the invention, the first component is afirst siderail and the second component is a second siderail.

Illustratively according to the invention, the first component is one ofan elevating frame and a siderail supported by the elevating frame, andthe second component is the other of the elevating frame and thesiderail.

Illustratively according to the invention, the first component is one ofa footboard and a siderail, and the second component is the other of thefootboard and the siderail.

According to another illustrative embodiment of the invention, ahospital bed includes a first component, a second component configuredto move relative to the first portion along a path of travel, and adetector supported by one of the first component and the secondcomponent, the detector configured to detect an obstacle within the pathof travel of the second component and provide a control signal inresponse thereto. A control unit is in communication with the detectorand is configured to prevent relative movement of the first and secondcomponents in response to the control signal.

Illustratively according to the invention, an emitter is supported byone of the first component and the second component, the emitter beingconfigured to generate a wireless signal. The emitter is illustrativelysupported by the first component and the detector is supported formovement with the second component.

Further illustratively according to the invention, the detectorcomprises a camera configured to capture images of the second componentalong the path of travel. The control unit is configured to compare theimages captured by the camera to predefined images to determine thepresence of an obstacle within the path of travel.

According to a further illustrative embodiment of the invention, apatient support apparatus comprises a first component, a secondcomponent configured to move relative to the first component along apath of travel, and an emitter supported by one of the first componentand the second component. The emitter is configured to transmit awireless signal having a pulsed portion of a predetermined frequency andduration. A detector is configured to detect the wireless signal, thedetector being configured to provide an indication if it fails to detectthe pulsed portion of the wireless signal.

Illustratively according to the invention, a control unit is configuredto prevent movement of the second component relative to the firstcomponent when the detector fails to detect the pulsed portion of thewireless signal. Further illustratively, the pulsed portion of thewireless signal has a frequency of approximately 57 MHz and a durationof approximately 600 microseconds.

According to another illustrative embodiment of the invention, a patientsupport apparatus comprises a first component, a second componentconfigured to move relative to the first component along a path oftravel, and a force sensing switch supported by one of the firstcomponent and the second component. The force sensing switch isconfigured to provide an indication if it detects the application of apredetermined force thereto.

Illustratively according to the invention, a control unit is configuredto prevent movement of the second component relative to the firstcomponent when the force sensing switch detects the application of thepredetermined force.

Additional features and advantages of the present invention will becomeapparent to those skilled in the art upon a consideration of thefollowing detailed description of illustrative embodiments exemplifyingthe best mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figuresin which:

FIG. 1 is a perspective view of a hospital bed incorporating anillustrative embodiment of the obstacle detection device of the presentinvention;

FIG. 2 is a side elevational view of the hospital bed of FIG. 1, theopposite side elevational view being a mirror image thereof;

FIG. 3 is a foot end view of the hospital bed of FIG. 1;

FIG. 4 is a block diagram representation of the obstacle detectiondevice of FIG. 1;

FIG. 5 is a side elevational view in partial schematic of the hospitalbed of FIG. 1, illustrating the bed in a fully raised position and withpotential obstacles positioned in detection paths of the variousreceivers;

FIG. 6 is a side elevational view in partial schematic similar to FIG.5, illustrating the bed in a lowered position;

FIG. 7 is a side elevational view in partial schematic similar to FIG.5, illustrating the bed in an intermediate position;

FIG. 8 is a foot end view in partial schematic of the hospital bed ofFIG. 5, illustrating the bed in a fully raised position and withpotential obstacles positioned in detection paths of the variousreceivers;

FIG. 9 is a flow chart illustrating the method operation associated withthe obstacle detection device of FIG. 1;

FIG. 10 is a perspective view of a hospital bed incorporating a furtherillustrative embodiment of the obstacle detection device of the presentinvention;

FIG. 11 is a side elevational view of the hospital bed of FIG. 10, theopposite side elevational view being a mirror image thereof;

FIG. 12 is a perspective view of a hospital bed, with certain componentsremoved for clarity, incorporating a further illustrative embodimentobstacle detection device of the present invention;

FIG. 13 is a partially exploded perspective view similar to FIG. 12,with the frame covers raised to illustrate the emitters and thedetectors of the obstacle detection device;

FIG. 14 is a side elevational view of the hospital bed of FIG. 12, withthe frame covers removed for clarity, the opposite side elevational viewbeing a mirror image thereof;

FIG. 15 is a foot end view of the hospital bed of FIG. 12, with theframe covers removed for clarity;

FIG. 16 is a rear perspective view of the foot end frame cover of thehospital bed of FIG. 12;

FIG. 17 is a perspective view of the left side head end frame cover ofthe hospital bed of FIG. 12, the right side head end frame cover being amirror image thereof;

FIG. 18 is an exploded perspective view of a housing of the obstacledetection device of FIG. 12;

FIG. 19 is a perspective view of a cover of the housing of FIG. 18;

FIG. 20 is a perspective view of a base of the housing of FIG. 18;

FIG. 21 is a block diagram representation of the obstacle detectiondevice of FIG. 12;

FIG. 22 is a timing diagram of an illustrative signal generated by theemitter of the obstacle detection device of FIG. 12;

FIG. 23 is an illustrative waveform generated by the detector of theobstacle detection device of FIG. 12 in response to the illustrativesignal of FIG. 22;

FIG. 24 is an illustrative waveform as received by the microprocessorafter the illustrative detector waveform of FIG. 23 passes through an RCfilter;

FIG. 25 is a perspective view of a hospital bed incorporating a furtherillustrative embodiment of the obstacle detection device of the presentinvention;

FIG. 26 is a perspective view of the hospital bed of FIG. 25 withcertain components removed for clarity;

FIG. 27 is a block diagram representation of the obstacle detectiondevice of FIG. 25;

FIG. 28 is a detailed perspective view, with a partial cutaway, of asensor of the obstacle detection device of FIG. 25;

FIG. 29 is a cross-sectional view taken along lines 29-29 of FIG. 28;and

FIG. 30 is a diagrammatic representation of the obstacle detectiondevice of FIG. 25.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring initially to FIGS. 1-3, a hospital bed 10 is illustrated asincluding the obstacle detection device 12 of the present invention. Thehospital bed 10 includes opposing right and left longitudinal side edges14 and 16 extending between a head end 18 and a foot end 20. In thefollowing description, the phrases “right side” and “left side” will beutilized to denote the relative location of an object positioned to lienearest the right side edge 14 and left side edge 16, respectively, ofthe bed 10. The phrase “head end” will be utilized to denote therelative location of an object positioned to lie nearest the head end 18of the hospital bed 10. Likewise, the phrase “foot end” will be used todenote the proximate location of a referenced object positioned to lienearest the foot end 20 of the hospital bed 10.

The hospital bed 10 includes a base module 22 having a base frame 24supported by conventional casters 25 which provide mobility to the bed10. The base frame 24 includes a right side member 21 and a left sidemember 23 connected by a foot end cross member 29 and a head end crossmember 31. An intermediate or elevating frame 26 is coupled to the baseframe 24 by first and second pairs of lift arms 28 and 30 in a mannerproviding for vertical movement of the elevating frame 26 relative tothe base frame 24. An articulating deck 36 is supported for movementrelative to the elevating frame 26. A mattress 38 is carried by thearticulating deck 36 and provides a sleeping or patient support surface40 configured to receive a patient.

A headboard 42 is illustratively supported by the elevating frame 26proximate the head end 18 of the bed 10 while a footboard 44 issupported by the elevating frame 26 proximate the foot end 20 of thebed. It should be appreciated that the headboard 42 and the footboard 44may alternatively be coupled to the base frame 24. Conventional firstand second siderails 46 and 47 are provided proximate the longitudinalside edges 14 and 16 of the bed 10. The first siderails 46 arepositioned proximate the foot end 20 of the bed 10, while the secondsiderails 47 are positioned proximate the head end 18 of the bed 10. Apair of arms 48 and 49 couple each of the siderails 46 and 47 to thearticulating deck 36 in a manner providing for relative verticalmovement therebetween.

The articulating deck 36 includes a head section 50, a seat section 52,a thigh section 54, and a foot section 56. Illustratively, the firstsiderails 46 are supported by the foot section 56, while the secondsiderails 47 are supported by the head section 50. As such, it should beappreciated that the siderails 46 and 47 move relative to each other asthe foot section 56 and the head section 50 of the articulating deck 36move relative to each other. The mattress 38 rests on the articulatingdeck 36 and includes a head portion 58, a seat portion 60, a thighportion 62, and a foot portion 64, each of which generally correspond tothe like-named portions of the deck 36, and each of which is generallyassociated with the head, seat, thighs, and feet of a patient supportedon the surface 40. Details of the articulating deck 36 are ofconventional design and may comprise those of the type disclosed in U.S.Pat. No. 6,336,235 to Ruehl, which is assigned to the assignee of thepresent invention and which is expressly incorporated by referenceherein.

The lift arms 28 and 30 are operably connected to a drive or liftingdevice 66 (FIG. 4) for causing the vertical movement of the elevatingframe 26 relative to the base frame 24. More particularly, the elevatingframe 26 is configured to move vertically between a raised position(FIG. 5) and a lowered position (FIG. 6). A plurality of intermediatepositions (FIG. 7) are available for the elevating frame 26 between theraised position and the lowered position. The lifting device 66 maycomprise a conventional mechanism of the type disclosed in U.S. Pat. No.3,958,383 to Adams et al. or U.S. Pat. No. 6,336,235 to Ruehl, both ofwhich are assigned to the assignee of the present invention and whichare expressly incorporated by reference herein.

With reference now to FIGS. 1-4, the obstacle detection device 12 of thepresent invention includes a first or right side detection unit 70,associated with the right side longitudinal edge 14 of the hospital bed10, a second or left side detection unit 72 associated with the leftlongitudinal side edge 16 of the bed 10, and a third or foot enddetection unit 74 associated with the foot end 20 of the bed 10. Theright side detection unit 70 is configured to generate a first opticalcurtain 76 (FIG. 2) while the left side detection unit 72 is configuredto generate a second optical curtain 78 substantially identical to thefirst optical curtain 76. Likewise, the foot end detection unit 74 isconfigured to generate a third optical curtain 80 (FIG. 3). A fourth orhead end detection unit (not shown) substantially identical to the footend detection unit 74 may likewise be provided adjacent the head end 18of the bed 10 for generating a fourth optical curtain (not shown)similar to the optical curtains 76, 78, and 80. Illustratively, eachdetection unit 70, 72, and 74 includes an emitter 82 coupled to the baseframe 24. The emitter 82 illustratively comprises a light source, suchas an infrared (IR) light emitting diode (LED). The light emitting diodemay be empirically selected based upon dimensions and operatingconditions of the bed 10.

Illustratively, an emitting diode Model No. SFH41SU available from OSRAMOpto Semiconductors of San Jose, Calif., may be utilized. However, itshould be appreciated that other conventional emitters, includingultrasonic, radar, and microwave may be substituted for the infraredemitters. A beam shaping lens 84 is positioned adjacent to each emitter82 for converting or shaping a beam of light emitted from the emitter 82into the respective optical curtain 76, 78, 80. The beam shaping lens 84may comprise a fresnel lens of the type well-known in the art.Illustratively, Model No. H43796 available from Edmund Scientific ofTonawanda, N.Y., may be utilized. It should be noted that a plurality ofemitters 82 may be utilized to form each respective optical curtain 76,78, 80, thereby eliminating the beam shaping lens 84.

The emitter 82 in combination with the lens 84 directs light apredetermined distance from the emitter 82 thereby minimizing spilloverto adjacent equipment. Moreover, each respective emitter 82 and lens 84define a perimeter including a predetermined width and height for theoptical curtains 76, 78, and 80. The predetermined height is defined toextend from an upper edge 86 to a lower edge 88 intermediate the baseframe 24 and the elevating frame 26. Illustratively, the predeterminedheight is equal to the distance between the base frame 24 and theelevating frame 26 when the elevating frame 26 is in its uppermostposition (FIG. 5) as defined by the lifting device 66.

A plurality of detectors 90, 92, 94 are associated with each emitter 82and are configured to receive or detect the respective optical curtain76, 78, and 80. The detectors 90, 92, and 94 are identified as DetectorA, Detector B, and Detector C, respectively in FIG. 4. Moreover, eachoptical curtain 76, 78, 80 is illustratively formed by a plurality ofindividual wireless infrared signals 96 (FIGS. 5-8) emitting from theemitter 82 and detectable by the detectors 90, 92, 94. Illustratively,Opto Sensor Model No. BPW-34F from OSRAM Opto-Semiconductors of SanJose, Calif., may be used for detectors 90, 92, 94. However, it shouldbe noted that other similar detectors may be readily substitutedtherefor. Moreover, as detailed below, detectors which are operableindependently of an emitter, such as proximity sensors or cameras, maybe substituted for the combined infrared detectors 90, 92, 94 andemitters 82.

Referring further to FIG. 4, a control unit 98 is provided incommunication with each emitter 82 and detector 90, 92, 94. In oneembodiment of the invention, each emitter 82 transmits randomlymodulated wireless infrared light rays or signals 96 to form arespective optical curtain 76, 78, 80. A source modulation orverification signal 99 is then transmitted through a conventionalcommunication link, such as hard wires (not shown) disposed within thebed base frame 24, to the control unit 98. If the intensity, spectrum ormodulation of the received wireless signal 96 at the detector 90, 92, 94does not match the verification signal 99, the control unit 98 inhibitsmovement of the bed 10 by the lifting device 66. As such, theverification signal 99 prevents external light sources, such as roomlights or sunlight, from interfering with the operation of the obstacledetection device 12.

An indicator 100 may be supported by the hospital bed 10 for providingan indication of the detection of the optical curtain 76, 78, 80 by thedetectors 90, 92, 94. More particularly, the indicator 100 may include aclearance indicator, illustratively in the form of a green light 102,which is activated by a clearance signal 103 supplied by the controlunit 98 to provide an indication of a clear detection path between theemitter 82 and the detectors 90, 92, 94. An obstruction indicator,illustratively in the form of a red light 104, may be provided toindicate a failure of one of the detectors 90, 92, 94 to receive theappropriate wireless signal 96 of the optical curtains 76, 78, 80. Theobstruction indicator 104 is activated by an obstruction signal 105supplied by the control unit 98. It should be appreciated that theindicator 100 may comprise a single bi-color red/green status indicator.Alternatively, other indicators, such as an audible alarm or any otherdevice which may provide an indication of the presence of an obstacle inthe detection path, may be readily substituted for the obstructionindicator light 104.

With reference to FIGS. 5-9, the operation of the obstacle detectiondevice 12 of the present invention is described in greater detail. Asillustrated in FIG. 9, the process begins at block 202 upon activationof the obstacle detection device 12. The process continues to block 204where the respective emitters 82 are activated. At block 206, theoptical curtains 76, 78, 80 are formed by passing a light beamcontaining rays or signals 96 produced by the respective emitters 82through the associated beam shaping lenses 84.

Continuing at block 208, the respective receivers 90, 92, 94 areactivated. The receivers 90, 92, 94 determine whether the respectivewireless curtain 76, 78, 80 is detected. If the curtain 76, 78, 80 isdetected, then the process continues to block 212 where verticalmovement of the elevating frame is permitted by the control unit 98. Atblock 214, the clearance indicator 102 is activated in response to theclearance signal 103 supplied by the control unit 98.

If one of the wireless curtain 76, 78, 80 is not detected by therespective detectors 90, 92, 94 at block 210, then the respectivedetector 90, 92, 94 sends an interruption signal 106 to the control unit98. The process continues to block 216 where the control unit 98generates a stop signal 108. At block 218, the elevating frame liftingdevice 66 is deactivated in response to the stop signal 108. At block220, the obstruction indicator 104 is activated in response to theobstruction signal 105 supplied by the control unit 98.

FIG. 5 illustrates the hospital bed 10 in a fully raised position.Moreover, the elevating frame 26 is raised to its uppermost position bythe lifting device 66 coupled 5 to the lift arms 28, 30. FIG. 6, inturn, illustrates the elevating frame 26 of the hospital bed 10 in itslowermost position wherein the elevating frame 26 is lowered to itsposition nearest the base frame 24 through operation of the liftingdevice 66 and the lift arms 28, 30, 32, 34. FIG. 7 illustrates thehospital bed 10 with the elevating frame 26 in a intermediate positionbetween the uppermost position of FIG. 5 to the lowermost position ofFIG. 6.

It should be noted that the lifting device 66 may be provided withposition sensors (not shown) configured to provide feedback positionsignals to the control unit 98 providing an indication of the relativevertical position of the elevating frame 26. Such position sensors arewell-known in the art and may be utilized with the obstacle detectiondevice 12 of the present invention to prevent the elevating frame 26from moving outside of the range of the optical curtains 76, 78 and 80.

As noted above, the receivers 90, 92, 94 for each optical curtain 76,78, 80 are configured to receive wireless signals 96 making up orforming the respective curtains 76, 78, 80. The wireless signals 96travel along a plurality of detection paths from the emitter 82 to thereceivers 90, 92, 94. Representative wireless signals 96 a, 96 b, 96 c,96 d and 96 e are illustrated in FIGS. 5 and 8. Potential obstacles arerepresented by reference numerals 114, 116 and 118 in FIG. 5 and areplaced within the respective detection paths of signals 96 a, 96 c, and96 e. The obstacles 114, 116, 118 prevent the wireless signals 96 a, 96c, and 96 e of the optical curtains 78 and 80 from reaching therespective detectors 90, 92, 94. The obstacles 114, 116, 118 maycomprise a person, medical instruments or any other object found withina hospital room.

FIGS. 10 and 11 illustrate a hospital bed 310 including an alternativeembodiment obstacle detection device 312 of the present invention. Theobstacle detection device 312 includes a first or right side detectionunit 370 associated with the right longitudinal side edge 14 of thehospital bed 310, a second or left side detection unit 372 associatedwith the left longitudinal side edge 16 of the bed 310, and a third orfoot end detection unit 374 associated with the foot end 20 of the bed310. The right side detection unit 370 is configured to generate a firstoptical curtain 376, while the left side detection unit 372 isconfigured to generate a second optical curtain 378. Likewise, the footend detection unit 374 is configured to generate a third optical curtain380. A fourth or head end detection unit (not shown) may be providedadjacent the head end 18 of the bed 310 for generating a fourth opticalcurtain (not shown) similar to the optical curtains 376, 378, and 380.

Illustratively, each detection unit 370, 372, and 374 of the obstacledetection device 312 includes a first or lower support 326 including aplurality of spaced apart emitters 328. Each emitter 328 preferablycomprises a self-contained infrared light-emitting diode. The emittersproduce a beam of light 330 upwardly toward the elevating frame of thebed 10. As illustrated in FIGS. 10 and 11, each beam of light 330 isdiscrete and spaced apart from adjacent beams of light 330.Collectively, the plurality of beams of light 330 define the respectiveoptical curtains 376, 378, and 380.

Each detection unit 370, 372, and 374 of the optical detection device312 further includes a second or upper support 332 including a pluralityof detectors 334. Each detector 334 is associated with one of theemitters 328 and is configured to receive or detect the respective lightbeam 330 defining the optical curtains 376, 378, and 380.

In a manner similar to that detailed above, if an obstacle is located inthe optical curtain 376, 378, 380 between one of the emitters 328 anddetectors 334, such that one of the light beams 330 is interrupted, thenthe control unit 98 prevents the lifting device 66 from verticallymoving the elevating frame 26.

It should be noted that the optical curtains 376, 378, and 380 of theobstacle detection device 312 require that the light beams 330 beaccurately aligned between the emitters 328 and the detectors 334throughout the full path of travel of the elevating frame 26. It may beappreciated, non-linear movement of the elevating frame 26 relative tothe base frame 24 may cause the respective emitters 328 and detectors334 to become mis-aligned, thereby resulting in a signal to the controlunit 98 that an obstacle is positioned within the optical curtain 376,378, 380. Such false optical detection signals are less likely to occurusing the earlier embodiment having substantially uniform opticalcurtains 76, 78, 80.

The individual detection units 370, 372, and 374 of the obstacledetection device 312 may comprise the EASY-GUARD™ grid system availablefrom Banner Engineering Corp. of Minneapolis, Minn. However, it shouldbe appreciated that other similar devices may be substituted therefor.

FIGS. 12 and 13, illustrate portions of a hospital bed 410 including afurther illustrative embodiment obstacle detection device 412 of thepresent invention. The obstacle detection device 412 includes a first orright side detection unit 470 associated with the right longitudinalside edge 14 of the hospital bed 410, a second or left side detectionunit 472 associated with the left longitudinal side edge 16 of the bed310, and a third or foot end detection unit 474 associated with the footend 20 of the bed 310. The right side detection unit 470 is configuredto detect an obstacle proximate the top of the right side member 21 ofthe base frame 24, while the left side detection unit 472 is configuredto detect an obstacle along the top of the left side 23 of the baseframe 24. Likewise, the foot end detection unit 474 is configured todetect an obstacle in front of the foot end cross member 29 of the baseframe 24 at the foot end 20 of the bed 410. It should be appreciatedthat a fourth or head end detection unit (not shown) may be providedadjacent the head end 18 of the bed 410 for detecting an obstacle behindthe head end cross member 31 of the base frame 24 of the bed 410.

As shown in FIGS. 13-15 and 21, each detection unit 470, 472, 474 of theobstacle detection device 412 includes an emitter 482 a, 482 b, 482 cand an associated detector 490 a, 490 b, 490 c. Each emitter 482illustratively comprises a self-contained infrared (IR) light-emittingdiode (LED) 483 coupled to an emitter microprocessor 485 which generatesan infrared (R) signal that is configured to be received by theassociated detector 490. The microprocessor 485 illustratively comprisesa conventional eight-bit microprocessor and may comprise Part No.MC68HC908QT1CDW available from Motorola of Schaumburg, Ill. A voltageregulator 487 is used to interface the microprocessor 485 to an 8.2 voltinput provided by the power source 488 of a power supply module 489. Theoutput of the microprocessor 485 interfaces with the LED 483, whichconverts the electrical signal into an optical one.

The detector 490 includes an IR sensor 491 which is configured toreceive the optical signal emitted from the emitter 482 and convert theoptical signal to an electrical signal. Illustratively, the sensor 491is an infrared photo diode configured to observe a specific signalfrequency and may comprise infrared detector Part No. GP1UM267XKavailable from Sharp Microelectronics of Camas, Wash. The IR sensor 491is interfaced to the 8.2 volt power source 488 via a conventionalregulator 492. The output of the detector 490 is routed through a buffer493 and to the power supply module 489 for processing in the mannerdescribed herein.

While the illustrative emitters 482 and detectors 490 utilize infraredlight, it should be appreciated that other wireless signals may besubstituted therefore. More particularly, other forms of electromagneticradiation, such as ultrasonic, radar, and microwave, may be substitutedfor IR light.

With reference to FIGS. 12, 13, and 16-20, each emitter 482 and detector490 is received within a housing 494. Each housing 494 includes a cover495 coupled to a base 498. The base 498 includes a mounting aperture 500configured to receive a fastener 502 for securing the base 498 to anaperture 503 formed in the base frame 24 of the bed 410. A locating peg504 extends downwardly from a lower surface of the base 498 and isconfigured to be received within an aperture 506 formed in the baseframe 24 of the bed 410. As such, the combination of the fastener 502received within the aperture 503 and the locating peg 504 receivedwithin the aperture 506 provides for the proper orientation and couplingof the housing 494 relative to the base frame 24. The base 498 furtherincludes four side walls 508 having a pair of notches or slots 510formed in a pair of opposing ones of the side walls 508 b and 508 d.

The cover 496 includes four side walls 512 and a top wall 514. A pair oflocking tabs 516 are resiliently supported by an opposing pair of theside walls 512 b and 512 d and are configured to lockingly engage withthe notches 510 of the base 498. Cooperating slots 518 and 520 areformed within the cover 496 and base 498 and are configured to receivecomponents, as supported on a circuit board 522, of the respectiveemitter 482 and detector 490. A pair of apertures 524 are formed withinone of the side walls 512 a of the cover 496 and are aligned with theLED 483 of the emitter 482 or the sensor 491 of the detector 490. Theapertures 524 are positioned and sized for the efficient transmission ofinfrared light without incurring substantial interference from externallight sources. Illustratively, the apertures 524 have a diameter of 3.18millimeters (0.125 inches) and are positioned approximately 24.2 mm(0.953 inches) in front of the mounting slots 518 and 520 for therespective circuit board 522.

With reference to FIGS. 12, 13, 16, and 17, the respective housings 440are protected from fluid ingress by caster or frame covers 526, 528, 530that cover portions of the base frame 24 proximate the head and footends 18 and 20. Each head end frame cover 526 and 528 includes a housing531 having side walls 532 connected to a top wall 534. One of the sidewalls 532 includes an opening 536 aligned with one of the apertures 524in one of the housings 494 associated with the right and left sidedetection units 470 and 472. A transparent window 538, illustratively aclear thermoplastic material, is fixed within the opening 536 to preventthe passage of fluid therethrough, while permitting the passage ofinfrared light from the emitter 482 to the detector 490. The window 538may be fixed in place using conventional methods, such as ultrasonicwelding or adhesives. A clearance slot 540 may be formed in another oneof the side walls 532 of the frame covers 526 and 528 to provideclearance for the brake/steer pedals 542 of the hospital bed 410, asneeded.

The foot end frame cover 530 includes first and second housings 544 and546 coupled together by a connecting member 548. Each housing 544 and546 includes side walls 550 coupled to a top wall 552, and a pair ofopenings 554 and 556 formed within different ones of the side walls 550.The openings 554 are associated with one of the apertures 524 of thefoot end housings 494 of the right and left side detection units 470 and472. The openings 556 are associated with one of the apertures 524 ofthe housings 494 associated with the foot end detection unit 474.Windows 538 are illustratively fixed within the openings 554 and 556 asdetailed above.

As illustrated in FIGS. 12 and 13, the right and left side detectionunits 470 and 472 may have their emitters 482 positioned at the head end18 and foot end 20 of the hospital bed 410, respectively. As such, thetransmission of infrared light from the emitters 482 of the right sidedetection unit 470 and the left side detection unit 472 will be inopposite directions (as shown by arrows 557 in FIG. 13) in order toreduce the possibility of cross talk between the two detection units 470and 472. Likewise, the emitter 482 of the foot end detection unit 474does not direct infrared light toward the detectors 490 of the right andleft side detection units 470 and 472.

To begin operation of the obstacle detection device 412, a controller ormicroprocessor 558 of the power supply module 489 initializes thevarious parameters and disables all interrupts. The power source 488 ofthe power supply module 489 supplies each emitter 482 with the requiredpower of 8.2 volts. The microprocessor 485 of each emitter 482 is usedto cause the LED 483 to generate an IR pulse signal 560 of the typeillustrated in FIG. 22. Illustratively, the signal 560 includes a 600microsecond pulsed portion 561 having a 57 kHz signal with a 50 percentduty cycle. A two millisecond delay follows the 57 kHz pulse with theoutput low. Such a pulse sequence repeats indefinitely. An internal busclock (not shown) illustratively runs at 3.2 MHz. As such, this providesan instruction cycle time of 312.5 nanoseconds.

The detector 490 is configured to look for a 056.8 diz signal, whichtranslates into 17.66 microseconds per pulse, or 8.803 microseconds perstate. The number of instruction cycles per state is determined by thefollowing formula:

Instruction cycles=total time/instruction cycle time

By inserting the above values for total time of 8.803 microseconds andinstruction cycle time of 312.5 nanoseconds, the number of instructioncycles is determined to be 28.17. Using 28 cycles per state provides atotal pulse time of 17.5 microseconds which equates to 57.14 kHz. A loopthat generates the 57 kHz IR signal is run 34 times, thereby giving atotal time of 595 microseconds.

The detector 490 is configured to look for the pulse signal 560including a pulsed portion or an IR signal burst 561 at a specificfrequency. When the signal 560 is detected with the appropriatefrequency component, the output of the detector 490 becomes active,effectively demodulating the transmitted signal. The detector 490includes a built-in frequency filter having a range of 53.6 kHz to 60kHz (56.8+3.2 kHz).

In addition to a band-pass filter, the IR detector 490 adjusts itssensitivity level proportionately to the strength of the incident lightsignal. This helps further filter noise signals that may be present inthe 56.8 kHz range.

The IR detector 490 filters the incident light to allow only the wavelength associated with IR to come into contact with the internal photodiode or sensor 491. This helps filter out the effects of sunlight,incandescent lighting, and fluorescent lights.

Upon detecting the appropriate wave length or frequency pulse signal560, the detector 490 provides an essentially demodulated signal 562such as that illustrated in FIG. 23. The signal illustratively has ahigh value of approximately 5 volts.

The demodulated signal 562 from the detector 490 is then transmitted toa Resistor-Capacitor (RC) filter 564 comprising part of the power supplymodule 489. The RC filter 564 converts the signal 562 of FIG. 23 to awaveform 566 such as that illustrated in FIG. 24. The waveform of FIG.24 has a nominal value of approximately 3.8 volts.+−.0.5 volts.Illustratively, the RC filter 564 is of conventional design and includesa 100 kohm resistor and a 0.1 μF capacitor. The output from the RCfilter 564 passes through a conventional analog to digital (A/D)converter (not shown) on its way to the microprocessor 558.

If the RC filter output drops below 3.3 volts, then the microprocessorknows that an obstacle has blocked the IR light path between the emitter482 and the detector 490, or that a fault condition exists, such as theemitter 482 or detector 490 not functioning properly. In either case,the microprocessor 558 functions by activating an indicator 100 anddisabling the lifting device 66 from further lowering of the patientsupport as detailed herein.

It should be appreciated that each emitter 482 and detector 490 could beconfigured to send and receive signal waveforms having different bit orpulse patterns, including different pulse frequencies and pulsedurations, in order to further limit the possibility of cross talkbetween different emitters and detectors. As may be appreciated, sincethe detectors 490 are configured to detect a frequency rather than anintensity, interference from external light sources is reduced.Furthermore, by looking for frequency, similar emitters 482 anddetectors 490 may be used for obstacle detection for a wide range ofdistances between the respective emitters 482 and detectors 490.

Referring now to FIGS. 25-30, a further illustrative embodiment obstacleor interference detection device 612 is shown coupled to the base frame28 of the patient support 410. The interference detection device 612illustratively includes first and second sensors 614 and 616 which arecoupled to upper surfaces 618 and 620 of the longitudinally extendingfirst (right) and second (left) side members 25 and 27 of the base frame24, respectively. While in the following description, first and secondsensors 614 and 616 are illustrated as being associated with the sidemembers 25 and 27 of the patient support 410, it should be appreciatedthat additional sensors could be positioned adjacent the head end 18 andthe foot end 20 of the patient support 410.

Each sensor 614 and 616 is configured to provide an interferencedetection signal to a control system 622 in the event that it detects anobstacle or determines that a fault condition exists. More particularly,each sensor 614 and 616 is configured to provide the interferencedetection signal to control system 622 upon detecting that an object,such as an individual's foot, is supported on one of the upper surfaces618 and 620 of the base frame 24. As described in greater detail below,the sensors 614 and 616 are configured to generate an interferencedetection signal only when a predetermined sufficient force is appliedthereto or when a fault condition occurs. As such, the sensors 614 and616 avoid generating false interference detection signals which couldimpact the normal operation of the patient support 410.

Referring further to FIGS. 28 and 29, each sensor 614 and 616illustratively includes a force sensing tape switch 624 including upperand lower contacts 626 and 628 which extend in substantially parallelrelation in a longitudinal direction above the side members 25 and 27 ofthe base frame 24. Each contact 626 and 628 is electrically conductiveand is in electrical communication with control system 622 throughconventional wires 630 and 632, respectively. Further, the upper contact626 is resilient so that a downwardly acting vertical force 634 willcause it to deflect into electrical contact with the lower contact 628,and upon removal of the force 634 the upper contact 626 will return toits original position in spaced relation to the lower contact 628.Illustratively, each contact 626 and 628 is formed from a thin sheet orlayer of stainless steel. A pair of isolation spacers 636 and 638 arepositioned intermediate the upper and lower contacts 626 and 628 alongopposing longitudinally extending side edges 640 and 642 thereof. Assuch, the isolation spacers 636 and 638 define a central void 644through which the upper contact 626 may be deflected into electricalcontact with the lower contact 628. The isolation spacers 636 and 638may be formed of any electrically insulative material, and areillustratively formed from either a Mylar® film or conventionaladhesive.

The lower contact 628 is secured to a base 646, illustratively formedfrom an electrically insulative material to prevent electricalcommunication between the lower contact 628 and the base frame 24. Anadhesive 648 may be utilized to secure the lower contact 628 to the base646. In one illustrative embodiment, the base 646 is made from athermoplastic material and formed as an unshaped channel. The base 646is secured to a respective upper surface 618, 620 of the base frame 24,illustratively through the use of an adhesive, although otherconventional fastening means, such as screw or bolts, may likewise beused. A potting compound 650, illustratively an epoxy, is receivedwithin the base 646 and encapsulates the switch 624 formed by the upperand lower contacts 626 and 628 and the isolation spacers 636 and 638.

As illustrated in FIGS. 28 and 29, the potting compound 650 does notfill the void 644 between the upper and lower contacts 626 and 628.Further, the potting compound 650 defines an upper surface 652 of thesensor 614. The material and dimensions of the potting compound 650 andthe upper contact 628 are selected to provide a sufficient resiliencysuch that when a predetermined sufficient force is applied to the uppersurface 652, the potting compound 650 causes the upper contact 626 tomove downwardly into electrical communication with the lower contact628. In an illustrative embodiment, the predetermined sufficient forceis set to be approximately 3.4 lbs.

Each sensor 614 and 616 is configured to detect not only a force exertedby an obstacle, but also a switch fault condition. More particularly,each sensor 614 and 616 is configured to provide a logic high value tocontrol system 44 when an obstacle is not detected, and the switch 624is open, and a logic low value when an obstacle is detected, and theswitch 624 is closed. Based on the signal received from the obstacledetection device 612, control system 622 will prevent the lowering ofthe intermediate or elevating frame 26 relative to the base frame 24.More particularly, the logic low value represents the interferencedetection signal to control system 622. As detailed below, this logiclow value may occur when the switch 624 is closed or when the switch 624is in a fault condition.

Referring to FIG. 30, a schematic representation of the first sensor 614of the obstacle detection device 612 is shown. It should be appreciatedthat the second sensor 616 is substantially identical. The upper andlower contacts 626 and 628 are shown as embodied within the switch 624.As stated previously, the upper and lower contacts 626 and 628 are madeof an electrically conductive material and are spaced apart at theirsides edges 640 and 642 by isolation spacers 636 and 638. However, theupper and lower contacts 626 and 628 are capable of contacting eachother within the central void 644 positioned between the contacts 626and 628. As detailed above, the upper contact 626 is configured tocontact the lower contact 628 when an obstacle exerts a sufficient forceagainst the upper surface 652 of the potting compound 650. As such, theswitch 624 is open when the upper and lower contacts 626 and 628 remainspaced apart, and the switch 624 is closed when the upper contact 626 isbrought into contact with the lower contact 628 by the application of asufficient downward force against the upper surface 652.

As shown in FIG. 30, the lower contact 628 is electrically connected toa ground 654. The upper contact 626 is connected to a voltage supply 656through a first resistor 658, illustratively having a value of 270 ohms.The voltage supply 656 may form part of the control system 622. Further,the upper and lower contacts 626 and 628 are connected together by asecond resistor 660, illustratively having a value of 1 kohm. A voltageoutput signal 662 is taken at the upper contact 626 and then sent to anAnalog to Digital (A/D) converter 664 to generate a logic signal forcontrol system 622. The A/D converter 664 may be incorporated within thecontrol system 622.

When the force exerted by an obstacle does not bring the upper contact626 into contact with the lower contact 628, the switch 624 is open andthe circuit shown in FIG. 30 is a voltage divider. In an illustrativeembodiment, the voltage supply 656 is a five volt supply and the valuesof first and second resistors 658 and 660 are selected such that avoltage value corresponding to a high logic value is measured at theupper contact 626. In one embodiment, the measured voltage is 3.9V. Whenan obstacle brings the upper contact 626 in contact with the lowercontact 628, the switch 624 is closed and the entire voltage of thevoltage supply 656 is dropped over the first resistor 658 such that thevoltage value measured at the upper contact 626 corresponds to a logiclow value. Likewise, should a break or similar fault occur within theswitch 624, the voltage of the voltage supply 656 is dropped over thefirst resistor 658 such that the voltage value measured at the uppercontact 626 will correspond to a logic low value. In any of thesesituations, whether the switch 624 is open, the switch 624 is closed, orthe switch 624 is in a fault condition, the A/D converter 664 convertsthe analog voltage signal measured at the upper contact 626 and convertsit into either a logic high value or a logic low value.

In response to the interference detection signal as represented by alogic low value, control system 622 will prevent the lowering of theelevating frame 26 relative to the base frame 24. Moreover, the logiclow value indicates that either an obstacle is supported on the baseframe 24 or that the switch 624 is not operating properly and is in afault condition. As such, in order to avoid potential damaging impactwith the detected obstacle, control system 622 prevents lifting device66 from operating to lower the elevating frame 26. In an illustrativeembodiment, control system 622 permits continued operation of thelifting device 66 to raise the elevating frame 26. Further, uponreceiving the interference detection signal, control system 622 mayinstruct the lifting device 66 to raise the elevating frame 26 for apredetermined time period, illustratively 2 seconds, while preventingoperation of the lifting device 66 to lower the elevating frame 26.Raising the elevating frame 26 for a time period after an obstacle hasbeen detected, provides for the immediate and automatic movement of theframe 26 in a direction away from the detected obstacle.

While the sensors 614 and 616 of the interference detection device 612are illustratively positioned on the base frame 24, it should beappreciated that the sensors 614 and 616 could likewise be positioned ona lower surface of the elevating frame 26. Further, the interferencedetection device 612 may be utilized to detect obstacles between any twoportions of a patient support apparatus which move relative to eachother. For example, the interference detection device 612 may be usedbetween the foot end and head end siderails 46 and 47, between the headend siderails 47 and the headboard 42, and between the foot endsiderails 46 and the footboard 44.

In a further alternative embodiment of the obstacle detection device 12of the present invention, the detectors 90, 92, 94 may comprise camerasutilizing vision technology to detect obstructions. More particularly,the camera captures images as the elevating frame 26 moves along itspath of travel. The images captured by the camera are compared by thecontrol unit 98 to predefined images of the elevating frame 26 movingalong the path of travel with no obstructions present. If each capturedimage fails to substantially match a corresponding predefined image,then the control unit 98 generates the stop signal 108 to preventmovement of the elevating frame 26 in the manner detailed above.

In yet another illustrative embodiment of the obstacle detection device12 of the present invention, the detectors 90, 92, 94 may compriseconductors, such as fiber optic cables, each having a property thatchanges between a first state and a second state upon movement of bedframe components. Additional details of such a conductor are disclosedin U.S. patent application Ser. No. 09/791,936, filed Feb. 23, 2001, nowU.S. Pat. No. 6,662,391, which is assigned to the assignee of thepresent invention and which is expressly incorporated by referenceherein.

While the foregoing illustrative description details application of theobstacle detection device 12 of the present invention for detecting anobstacle between an elevating frame 26 and a base frame 24, this in noway is intended to limit the scope of the invention. Moreover, theobstacle detection device 12 may be utilized to detect obstacles betweenany two portions of a patient support apparatus which move relative toeach other. For example, the obstacle detection device 12 may be usedbetween the first and second siderails 46 and 47, between the firstsiderail 46 and the footboard 44, and between the second siderail 47 andthe headboard 42.

Although the invention has been described in detail with reference tocertain illustrated embodiments, variations and modifications existwithin the scope and spirit of the invention as described and as definedin the following claims.

1. A patient support apparatus comprising: a base frame; an elevatingframe disposed in spaced relation to said base frame; a lifting deviceconfigured to move said elevating frame relative to said base frame; anemitter coupled to one of said base frame and said elevating frame, saidemitter being configured to generate a wireless signal; and a receivercoupled to one of said base frame and said elevating frame, saidreceiver associated with said emitter and configured to detect saidwireless signal.
 2. The patient support apparatus of claim 1, furthercomprising a control unit in communication with said lifting device andsaid receiver, said control unit configured to prevent operation of saidlifting device if said receiver fails to detect said wireless signal. 3.The patient support apparatus of claim 1, wherein said emitter generatesan optical curtain positioned intermediate said base frame and saidelevating frame.
 4. The patient support apparatus of claim 1, whereinsaid emitter comprises an infrared light source.
 5. The patient supportapparatus of claim 4, further comprising a lens positioned proximatesaid infrared light source and configured to convert light emitted fromsaid infrared light source to an optical curtain.
 6. The patient supportapparatus of claim 5, wherein said lens comprises a fresnel lens.
 7. Thepatient support apparatus of claim 1, wherein said wireless signalincludes a modulated signal and said control unit compares saidmodulated signal to a predefined verification signal to preventinterference from external light sources.
 8. The patient supportapparatus of claim 1, wherein said receiver is configured to move withsaid elevating frame within a predefined vertical range.
 9. The patientsupport apparatus of claim 8, wherein said predefined vertical range isfrom said base frame to said elevating frame when said elevating frameis in a fully raised position.
 10. The patient support apparatus ofclaim 1, wherein: the emitter is configured to generate a plurality ofwireless signals in a plurality of signal paths; and a plurality ofreceivers are configured to detect said wireless signals along differentones of said signal paths, said control unit preventing movement of saidelevating frame when any of said plurality of receivers fail to detect awireless signal.
 11. The patient support apparatus of claim 10, whereinat least one of said receivers is supported for movement with saidelevating frame.
 12. The patient support apparatus of claim 11, whereinsaid emitter is supported by said base frame.
 13. A hospital bedcomprising: a first component; a second component configured to moverelative to said first component along a path of travel; a detectorsupported by one of said first component and said second component, saiddetector configured to detect an obstacle within said path of travel ofsaid second component without the obstacle contacting the detector, saiddetector configured to provide a control signal in response to detectingthe obstacle; and a control unit in communication with said detector andconfigured to prevent relative movement of said first and secondcomponents in response to said control signal.
 14. The hospital bed ofclaim 13, further comprising an emitter supported by one of said firstcomponent and said second component, said emitter configured to generatea wireless signal that is detected by the detector when the obstacle isabsent.
 15. The hospital bed of claim 14, wherein said emitter issupported by said first component and said detector is supported formovement with said second component.
 16. The hospital bed of claim 14,wherein said emitter comprises an infrared light source.
 17. Thehospital bed of claim 16, wherein said wireless signal includes a pulsedportion having a predefined frequency, and said receiver is configuredto detect said predefined frequency.
 18. The hospital bed of claim 17,wherein said pulsed portion has a frequency of approximately 57 MHz anda duration of approximately 600 microseconds.
 19. The hospital bed ofclaim 14, wherein said detector comprises a camera configured to captureimages of said second component along said path of travel.
 20. Thehospital bed of claim 19, wherein said control unit is configured tocompare the images captured by said camera to predefined images todetermine the presence of an obstacle within said path of travel.